Method of fabricating semiconductor devices

ABSTRACT

Provided is a method of fabricating a semiconductor device. The method includes forming an oxide film on a target layer, forming a first mask film on the oxide film, wherein the first mask film contains a semiconductor material and has a first thickness and a first etch selectivity with respect to the oxide film, forming a second mask film on the first mask film, wherein the second mask film contains a metal and has a second thickness smaller than the first thickness and a second etch selectivity larger than the first etch selectivity with respect to the oxide film, forming a second mask film pattern by patterning the second mask film, forming a first mask film pattern by patterning the first mask film, etching some portions of the oxide film by using the second mask film pattern as an etch mask film, and etching the rest of the oxide film by using the first mask film pattern as an etch mask film to form a hole, wherein the target layer is exposed via the hole.

This application claims the benefit of priority under 35 U.S.C. § 119from Korean Patent Application No. 10-2016-0134918, filed on Oct. 18,2016, in the Korean Intellectual Property Office, the disclosure ofwhich is incorporated herein by reference in its entirety.

BACKGROUND 1. Field of the Disclosure

The present disclosure relates to a method of fabricating asemiconductor device.

2. Description of the Related Art

So far, semiconductor devices have evolved so that they are driven withlower voltage but operate faster. In addition, the process offabricating semiconductor devices has continued to increase the degreeof integration. Accordingly, in a high integration semiconductor devicein a large scale, patterns have a micro-width and are spaced apart fromone another by a fine pitch.

As semiconductor devices become finer, pitches between holes, contactsor capacitors become increasingly narrow, and accordingly it isinevitable to form features having a high aspect ratio. Such featureshaving a high aspect ratio may include capacitors in a DRAM, channels ina vertical NAND (VNAND), and metal contacts formed in a variety ofsemiconductor devices.

In a DRAM device, for example, as the aspect ratio of the lowerelectrode of a capacitor has increased, there have been proposed manymethods for forming holes having a high aspect ratio in which thecapacitor is formed.

SUMMARY

Aspects of the present disclosure provide a method of fabricating asemiconductor device that includes a hole in which a capacitor having ahigh aspect ratio is formed by using different types of masks.

In some embodiments, the disclosure is directed to a method offabricating a semiconductor device, the method comprising: forming anoxide film on a target layer; forming a first mask film on the oxidefilm, wherein the first mask film contains a semiconductor material andhas a first thickness and a first etch selectivity with respect to theoxide film; forming a second mask film on the first mask film, whereinthe second mask film contains a metal and has a second thickness smallerthan the first thickness and a second etch selectivity with respect tothe oxide film larger than the first etch selectivity; forming a secondmask film pattern by patterning the second mask film; forming a firstmask film pattern by patterning the first mask film; etching firstportions of the oxide film by using the second mask film pattern as afirst etch mask film; and etching second portions of the oxide film byusing the first mask film pattern as a second etch mask film to form ahole, wherein the target layer is exposed via the hole.

In some embodiments, the disclosure is directed to a method offabricating a semiconductor device, the method comprising: forming anisolating film to define an active area in a substrate; forming a gatein the active area; forming an interlayer insulation film on thesubstrate, a bit line feature, and a landing pad in the interlayerinsulation film, wherein the landing pad is electrically connected tothe active area; forming an oxide film on the interlayer insulationfilm; forming a first mask film pattern on the oxide film and a secondmask film pattern on the first mask film pattern; forming a first holepenetrating the oxide film to a depth by using the second mask filmpattern; forming a second hole by etching a remaining portion of theoxide film by using the first mask film pattern, wherein the landing padis exposed via the second hole; and forming a capacitor electricallyconnected to the landing pad via the second hole.

In some embodiments, the disclosure is directed to a method offabricating a semiconductor device, the method comprising: forming anoxide film on an interlayer insulation film; forming a first mask filmon the oxide film, wherein the first mask film has a first thickness anda first etch selectivity with respect to the oxide film; forming asecond mask film on the first mask film, wherein the second mask filmhas a second thickness and a second etch selectivity with respect to theoxide film; forming a second mask film pattern by patterning the secondmask film; forming a first mask film pattern by patterning the firstmask film; forming a first hole penetrating the oxide film to a depth byusing the second mask film pattern as a first etch mask; forming asecond hole by etching a remaining portion of the oxide film by usingthe first mask film pattern as a second etch mask, wherein a landing padin the interlayer insulation film is exposed via the second hole; andforming a capacitor electrically connected to the landing pad via thesecond hole, wherein the first thickness is larger than the secondthickness and the first etch selectivity is smaller than the second etchselectivity.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and features of the present disclosure willbecome more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings, in which:

FIGS. 1 to 7 are cross-sectional views showing processing steps of amethod of fabricating a semiconductor device according to an exemplaryembodiment of the present disclosure; and

FIGS. 8 to 15 are cross-sectional views showing processing steps of amethod of fabricating a semiconductor device according to anotherexemplary embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The various pads described herein may be connected to internal circuitrywithin the device to which they are connected, and may transmit signalsand/or voltage to and/or from the device to which they are attached. Forexample, substrate pads disposed on the package substrate may connect torerouting and other electrical lines disposed within the packagesubstrate, and the pads disposed on the semiconductor chips may connectto an integrated circuit on one or more of the semiconductor chips. Thevarious pads described herein may generally have a planar surface at alocation for connecting to a terminal for external communicationsoutside of the device to which the pads are connected. The pads may beformed of a conductive material, such a metal, for example.

As used herein, items described as being “electrically connected” areconfigured such that an electrical signal can be passed from one item tothe other. Therefore, a passive electrically conductive component (e.g.,a wire, pad, internal electrical line, etc.) physically connected to apassive electrically insulative component (e.g., a prepreg layer of aprinted circuit board, an electrically insulative adhesive connectingtwo device, an electrically insulative underfill or mold layer, etc.) isnot electrically connected to that component. Moreover, items that are“directly electrically connected,” to each other are electricallyconnected through one or more passive elements, such as, for example,wires, pads, internal electrical lines, through vias, etc. As such,directly electrically connected components do not include componentselectrically connected through active elements, such as transistors ordiodes.

The term “buried” may refer to structures, patterns, and/or layers thatare formed at least partially below a top surface of another structure,pattern, and/or layer. In some embodiments, when a first structure,pattern, and/or layer is “buried” in a second structure, pattern, and/orlayer, the second structure, pattern, and/or layer may surround at leasta portion of the first structure, pattern, and/or layer. For example, afirst structure, pattern, and/or layer first may be considered to beburied when it is at least partially embedded in a second structure,pattern, and/or layer. It will be understood that, although the termsfirst, second, third etc. may be used herein to describe variouselements, components, regions, layers and/or sections, these elements,components, regions, layers and/or sections should not be limited bythese terms. Unless the context indicates otherwise, these terms areonly used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section, forexample as a naming convention. Thus, a first element, component,region, layer or section discussed below in one section of thespecification could be termed a second element, component, region, layeror section in another section of the specification or in the claimswithout departing from the teachings of the present invention. Inaddition, in certain cases, even if a term is not described using“first,” “second,” etc., in the specification, it may still be referredto as “first” or “second” in a claim in order to distinguish differentclaimed elements from each other.

Example embodiments may be described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized example embodiments (and intermediate structures). As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, example embodiments should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will typically have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature, their shapes are not intended to illustrate the actual shapeof a region of a device, and their shapes are not intended to limit thescope of the example embodiments.

FIGS. 1 to 7 are cross-sectional views for illustrating processing stepsof a method of fabricating a semiconductor device according to anexemplary embodiment of the present disclosure.

Referring to FIG. 1, a method of fabricating a semiconductor deviceaccording to an exemplary embodiment of the present disclosure includesforming an isolating film 15 on a substrate 10 to define an active area20; and forming a gate 30 buried in the active area 20. The method mayfurther include forming an interlayer insulation film on a target layer,where a target layer refers to a lower layer on which interlayerinsulation film is formed and may include one or more patterns or layersto form the target layer. For example, the method may include formingthe interlayer insulation film 50 on the isolating film 15 and theburied gate 30; forming a bit line feature 40 and a landing pad 60 inthe interlayer insulation film 50, and sequentially forming a stoppinginsulation film 70, an oxide film 100, a first mask film 110 and asecond mask film 120 on the interlayer insulation film 50. The substrate10 may be, for example, a bulk silicon substrate or a SOI(silicon-on-insulator) substrate. Alternatively, the substrate 10 may bea silicon substrate or may be a substrate made of other materials, suchas silicon germanium (SiGe), indium antimonide (InSb), lead-telluride(PbTe) compound, indium arsenide (InAs), indium phosphide (InP), galliumarsenide (GaAs) and gallium antimonide (GaSb). Alternatively, thesubstrate 10 may be formed by growing an epitaxial layer on a basesubstrate. In the following exemplary description, the substrate 10 is asilicon substrate.

The isolating film 15 may be formed in the substrate 10 to define theactive area 20. For example, the lower surface of the isolating film 15may be lower than the upper surface of the substrate 10, to define theactive area 20. In some embodiments, an upper surface of the isolatingfilm 15 may be at the same vertical level as the upper surface of thesubstrate 10. The isolating film 15 may include one of an oxide film, anoxynitride film and a nitride film, for example.

Forming a buried gate may include forming a trench in the active area20, and forming a gate insulation film 33, a gate electrode 31 and agate capping film 32 in the trench.

The gate electrode 31 may include a conductive material, for example.Examples of such a conductive material may include, but are not limitedto, doped polysilicon, titanium nitride (TiN), tantalum nitride (TaN),tungsten nitride (WN), titanium (Ti), tantalum (Ta), tungsten (W), etc.

The gate capping film 32 may include one of silicon oxide, siliconnitride and silicon oxynitride.

The gate insulation film 33 may include, but is not limited to, an oxidefilm. For example, the gate insulation film 33 may include a high-kdielectric film such as hafnium oxide, hafnium silicon oxide, lanthanumoxide, lanthanum aluminum oxide. The gate insulation film 33 maysurround the gate electrode 31 and the gate capping film 32. Forexample, the gate insulation film 33 may be formed on the surfaces ofthe trench, and the gate electrode 31 may be formed in a lower portionof the trench and the gate capping film 32 may be formed in an upperportion of the trench above the gate electrode 31.

The interlayer insulation film 50 may cover the upper surface of thesubstrate 10. The interlayer insulation film 50 may include an oxidefilm, for example. In addition, the interlayer insulation film 50 maysurround the side surfaces of the bit line feature 40 and the landingpad 60.

Forming the bit line feature 40 comprises forming a bit line contactplug 41 on the substrate 10, forming a bit line electrode 42 on the bitline contact plug 41, forming a bit line capping film 43 on the bit lineelectrode 42, and forming a bit line spacer 44 on either side of the bitline contact plug 41, the bit line electrode 42 and the bit line cappingfilm 43. The interlayer insulation film 50 may surround the sidesurfaces of the bit line spacer 44.

The bit line contact plug 41 may be, for example, formed by using anepitaxial growth process from the active area 20 of the substrate 10 toform single-crystal silicon. Alternatively, the bit line contact plug 41may be formed on the active area 20 such that it includes a dopedsemiconductor material, a conductive metal nitride and ametal-semiconductor compound.

For example, the bit line electrode 42 may be formed on the bit linecontact plug 41 such that it includes a conductive material such astungsten. Although not shown in the drawings, a barrier film including amaterial such as titanium, titanium nitride, tantalum and tantalumnitride may be formed between the bit line electrode 42 and the bit linecontact plug 41.

The bit line capping film 43 may be formed on the bit line electrode 42such that it includes silicon nitride, for example. The bit line cappingfilm 43 may serve as a mask used for patterning the line shapes of thebit line contact plug 41 and the bit line electrode 42.

The bit line spacer 44 may be formed, for example, by depositing siliconnitride on the side surfaces of a feature in which the bit line contactplug 41, the bit line electrode 42 and the bit line capping film 43 arestacked one on another.

Forming the landing pad 60 may include filling the trench formed in theinterlayer insulation film 50 with a doped semiconductor material suchas tungsten, a conductive metal nitride, a metal and ametal-semiconductor compound. Alternatively, the landing pad 60 may beformed by using an epitaxial growth process from the active area 20 ofthe substrate 10 to form single-crystal silicon. Doped regions areformed in the active area 20 in contact with the landing pad 60, whichmay server as source/drain regions.

Forming the stopping insulation film 70 may include forming siliconnitride, for example, on the interlayer insulation film 50, the bit linefeature 40 and the landing pad 60 via a deposition process. The stoppinginsulation film 70 may include a material having an etch selectivitywith respect to the interlayer insulation film 50 and the oxide film100.

Forming the oxide film 100 may include forming silicon nitride on thestopping insulation film 70, for example, via a deposition process. Insome exemplary embodiments, the oxide film 100 may be thicker than thestopping insulation film 70.

The first mask film 110 may be formed on the oxide film 100. In someexemplary embodiments of the present disclosure, the first mask film 110may be a silicon mask film. More specifically, the first mask film 110may include silicon or doped silicon. For example, the first mask film110 may include silicon doped with one of boron (B), carbon (C) andphosphorus (P).

Forming the first mask film 110 on the oxide film 100 may includeforming the above-described materials, e.g., via oxide film growth(diffusion), chemical vapor deposition (CVD).

The second mask film 120 may be formed on the first mask film 110. Insome exemplary embodiments of the present disclosure, the second maskfilm 120 may be a metal mask film. More specifically, the second maskfilm 120 may include, but is not limited to, tungsten (W), tungstennitride (WN), tungsten carbide (WC), aluminum (Al), aluminum oxide(Al₂O₃), titanium (Ti), titanium oxide (TiO), tungsten silicide (WSi),etc.

Forming the second mask film 120 may include depositing theabove-described material on the first mask film 110, e.g., via physicalvapor deposition (PVD), CVD, etc.

The first mask film 110 and the second mask film 120 may be used as etchmasks during an etching process of the oxide film 100 to be describedbelow. The first mask film 110 may have a first etch selectivity withrespect to the oxide film 100, while the second mask film 120 may have asecond etch selectivity with respect to the oxide film 100. In someembodiments of the present disclosure, the second etch selectivity maybe larger than the first etch selectivity. For example, in someembodiments, during an etch process of the oxide film 100, the secondmask film 120 including a metal mask film has an etch resistance largerthan that of the first mask film 110 including a silicon mask film.

As shown in FIG. 1, the first mask film 110 may have a first thicknessh1, and the second mask film 120 may have a second thickness h2. Thefirst thickness h1 of the first mask film 110 may be larger than thesecond thickness h2 of the second mask film 120. For example, the firstthickness h1 of the first mask film 110 may be approximately twice tothree times the second thickness h2 of the second mask film 120.Thickness may refer to the thickness or height measured in a directionperpendicular to a top surface of the substrate 10.

In some embodiments, the first thickness h1 of the first mask film 110may be between approximately 3 to 6 kilo-Angstrom (kA), and the secondthickness h2 of the second mask film 120 may be between approximately 1to 3 ka.

As described above, the second etch selectivity of the second mask film120 with respect to the oxide film 100 may be larger than the first etchselectivity of the first mask film 110. Accordingly, in order to etchthe oxide film 100 to the same depth by using the first and second maskfilms during a subsequent etch process of the oxide film 100, thethickness of the first mask film 110 may be larger than the thickness ofthe second mask film 120.

Referring to FIG. 2, by patterning the first mask film 110 and thesecond mask film 120, a first mask pattern 111 and a second mask pattern121 may be formed. For example, patterning the first mask film 110 andthe second mask film 120 may include forming a complex film including anoxide film, a carbon film and a capping film on the first mask film 110and the second mask film 120, forming a complex pattern on the complexfilm via a photoresist process, forming the second mask pattern 121 andthe first mask film pattern 111 by sequentially patterning the secondmask film 120 and the first mask film 110 using the complex pattern asan etch mask.

Like the first mask film 110 and the second mask film 120, the firstmask film pattern 111 may have the first thickness h1, and the secondmask film pattern 121 may have the second thickness h2. Like the firstmask film 110 and the second mask film 120, the first thickness h1 maybe different from the second thickness h2. For example, the firstthickness h1 of the first mask film pattern 111 may be approximatelytwice to three times the second thickness h2 of the second mask filmpattern 121.

Some portions of the upper surface of the oxide film 100 may be exposedvia the first mask film pattern 111 and the second mask film pattern121. The exposed portions of the oxide film 100 may overlap the landingpad 60 at least partially. For example, when viewed in a plan view, theexposed portions of the oxide film 100 may overlap portions of thelanding pad 60. This is because a process of forming a hole is carriedout on the exposed portions of the oxide film 100 such that a capacitorin the hole is electrically connected to the landing pad 60.

Referring to FIG. 3, a first etch process 300 of etching the oxide film100 partially may be carried out by using the second mask film pattern121 as an etch mask. As a result of the first etch process 300, a firsthole 130 may be formed that penetrates the oxide film 100 to a depth.

During the first etch process 300, an etchant for etching the oxide film100 may include, for example, C₄F₈ or C₄F₆ gas or a mixed gas thereof.

As a result of the first etch process 300, the second mask film pattern121 may also be damaged, such that the thickness of the second mask filmpattern 121 may be reduced. However, the second mask film pattern 121may not be completely removed via the first etch process 300.

Referring to FIG. 4, the second mask film pattern 121 remaining on thefirst mask film pattern 111 after the first etch process 300 iscompletely removed. The second mask film pattern 121 may be removed bywet etching. Specifically, the second mask film pattern 121 may beremoved by using a mixture of a hot sulfuric acid solution and astandard clean 1 (SC1) solution. By combining the wet etchants, thesecond mask film pattern 121 can be completely removed with no damage tothe oxide film 100 and the first hole 130 in the oxide film 100.

As the second mask film pattern 121 is completely removed, the uppersurface of the first mask film pattern 111 is exposed. Accordingly, thefirst mask film pattern 111 may be used as an etch mask during asubsequent process of further etching the oxide film 100.

Referring to FIG. 5, a second etch process 310 of etching the rest ofthe oxide film 100 may be carried out by using the first mask filmpattern 111 as an etch mask. As a result of the second etch process 310,a second hole 140 may be formed that penetrates the oxide film 100completely.

Performing the second etch process 310 may include removing the stoppinginsulation film 70 under the oxide film 100. For example, the secondetch process 310 may remove portions of the stopping insulation film 70located in the area where the second hole 140 is formed. As the portionsof the stopping insulation film 70 covering the landing pad 60 areremoved, the upper surface of the landing pad 60 may be exposed.

During the second etch process 310, the first mask film pattern 111 mayalso be damaged, such that the thickness of the first mask film pattern111 may be reduced.

During the second etch process 310, an etchant for etching the oxidefilm 100 and the stopping insulation film 70 may include, for example,C₄F₈ or C₄F₆ gas or a mixed gas thereof.

In the method of fabricating a semiconductor device according to theexemplary embodiment of the present disclosure, the oxide film 100 isetched by using the second mask film pattern 121 and the first mask filmpattern 111 as etch masks sequentially. By using both of the first maskfilm pattern 111 and the second mask film pattern 121, it is possible toform the second hole 140 having a high aspect ratio.

Typically, when the oxide film 100 is etched by using only the firstmask film pattern 111 including a silicon mask film, it may not bepossible to form a hole to a desired depth since the etch selectivity ofthe first mask film pattern 111 with respect to the oxide film isinsufficient. If the thickness of the first mask film pattern 111 isincreased to obtain a sufficient etching depth, the first mask filmpattern 111 may be tilted such that patterning may become defective.

On the other hand, when the oxide film 100 is etched by using only thesecond mask film pattern 121 including a metal mask film, the secondmask film pattern 121 may have a sufficient etch selectivity withrespect to the oxide film 100. However, the second mask film pattern 121including a metal may not be evenly formed, such that criticaldimensions (CD) of the holes in the oxide film 100 may not be uniform.

In the method of fabricating a semiconductor device according to theexemplary embodiment of the present disclosure, the first etch process300 is carried out by using the second mask film pattern 121 having thesecond etch selectivity larger than the first etch selectivity of thefirst mask film pattern 111 with respect to the oxide film 100. By usingthe second etch selectivity of the second mask film pattern 121, thefirst hole 130 having a sufficient depth is formed in the oxide film100.

Subsequently, the remaining second mask film pattern 121 is completelyremoved, and then the rest of the oxide film 100 is etched by using thefirst mask film pattern 111 as an etch mask, thereby forming the secondhole 140 penetrating the oxide film 100.

By carrying out the first and second etch processes 300 and 310 by usingboth of the first mask film pattern 111 and the second mask film pattern121, the thickness of the first mask film pattern 111 may be smallerthan that of the first mask film pattern 111 when it is solely used, andaccordingly the tilting of the first mask film pattern 111 can besuppressed.

On the other hand, as the rest of the oxide film 100 is etched by usingthe first mask film pattern 111 after the second mask pattern 121 iscompletely removed, it is possible to mitigate unevenness that may occurwhen the oxide film 100 is etched by using the second mask film pattern121.

As a result, by the method of fabricating a semiconductor deviceaccording to the exemplary embodiment of the present disclosure, it ispossible to form the second hole 140 having a high aspect ratio.

Subsequently, referring to FIG. 6, a lower electrode 150 is formed inthe second hole 140. Forming the lower electrode 150 may include, forexample, filling the second hole 140 with a conductive material, andthen removing the conductive material on the upper surface of the oxidefilm 100 via an etch-back process or chemical mechanical polishing(CMP), etc.

Referring to FIG. 7, the oxide film 100 around the lower electrode 150is completely removed, a dielectric film 170 is formed conformally overthe lower electrode 150 and the stopping insulation film 70, and anupper electrode 160 is formed such that it covers the dielectric film170 and the lower electrode 150 to form a capacitor 180.

Like the etch process of the oxide film 100 described above, removingthe oxide film 100 may include removing the oxide film 100 by using anetchant containing a C₄F₈ or C₄F₆ gas, or a mixed gas thereof.

Forming the dielectric film 170 may include, but is not limited to,forming a high-k material such as hafnium (Hf) or zirconium (Zr)conformally over the lower electrode 150 and the stopping insulationfilm 70. The dielectric film 170 may include, for example, at least oneof hafnium oxide, hafnium silicon oxide, hafnium oxynitride, zirconiumoxide, zirconium silicon oxide, tantalum oxide and titanium oxide.

Forming the upper electrode 160 may include forming a conductivematerial so that it covers the dielectric film 170 and the lowerelectrode 150. The upper electrode 160 may include a metal, a metalcompound, or a combination thereof.

By forming the lower electrode 150, the upper electrode 160 and thedielectric film 170, the capacitor 180 is formed.

As described above, by the method of fabricating a semiconductor deviceaccording to the exemplary embodiment of the present disclosure, it ispossible to form the second hole 140 having a high aspect ratio and thelower electrode 150 with which the second hole 140 is filled, therebyforming the capacitor 180 having a high aspect ratio. The capacitor 180having a high aspect ratio can having increased capacitance and canimprove the operation reliability of the semiconductor device.

FIGS. 8 to 15 are cross-sectional views for illustrating processingsteps of a method of fabricating a semiconductor device according toanother exemplary embodiment of the present disclosure. In the followingdescription, like reference numerals may denote features analogous tothose described in the above-described exemplary embodiment.

Referring to FIG. 8, an active area 20 is defined in a substrate 10 byan isolating film 15, and a buried gate 30 is formed in the substrate10. A landing pad 60, an interlayer insulation film 50 and a bit linefeature 40 are formed on the substrate 10 and the buried gate 30. Astopping insulation film 70, a first oxide film 200, a lower supporterfilm 201, a second oxide film 205, an upper supporter film 202, a firstmask film 210 and a second mask film 220 may be formed sequentially suchthat they cover the interlayer insulation film 50, the landing pad 60and the bit line feature 40.

In the method of fabricating a semiconductor device according to thisexemplary embodiment, the first oxide film 200 and the second oxide film205 may include the same material. Specifically, both of the first oxidefilm 200 and the second oxide film 205 may include silicon oxide.

The lower supporter film 201 may be formed between the first oxide film200 and the second oxide film 205. For example, the lower supporter filmmay be formed such that it is interposed between the first oxide filmand the second oxide film. The lower supporter film 201 may be formed bydepositing silicon nitride on the first oxide film 200, for example. Inthe semiconductor device fabricated by the method according to exemplaryembodiment, the lower supporter film 201 may support electrodes of acapacitor, which will be described in detail below.

The upper supporter film 202 may be formed between the second oxide film205 and the first mask film 210. For example, the upper supporter filmmay be formed such that it is interposed between the second oxide filmand the first mask film. The upper supporter film 202 and the lowersupporter film 201 may be formed by depositing the same material, butthis is not limiting. Like the lower supporter film 201, the uppersupporter film 202 may support electrodes of a capacitor included in thesemiconductor device fabricated by the method according to the exemplaryembodiment of the present disclosure.

The first mask film 210 and the second mask film 220 may be formedsequentially such that they cover the upper surface of the uppersupporter film 202. For example, the first mask film 210 may be formedon the upper supporter film 202, and the second mask film 220 may beformed on the first mask film 210. As described above, the first maskfilm 210 may include silicon or may be a silicon film containing silicondoped with boron, carbon, phosphorus, etc.

Forming the first mask film 210 on the upper supporter film 202 mayinclude forming the above-described materials via, e.g., oxide filmgrowth (diffusion), chemical vapor deposition (CVD), etc.

The second mask film 220 may include, for example, at least one oftungsten, tungsten nitride, tungsten carbide, aluminum, aluminum oxide,titanium, titanium oxide, tungsten silicide, etc.

Forming the second mask film 220 may include depositing theabove-described material on the first mask film 210 by, e.g., PVD, CVD,etc.

Like the above-described exemplary embodiment, the first mask film 210may have a first thickness h1, and the second mask film 220 may have asecond thickness h2 smaller than the first thickness h1. Specifically,the first thickness h1 of the first mask film 210 may be approximatelytwice to three times the second thickness h2 of the second mask film220.

In addition, the etch selectivity of the second mask film 220 withrespect to the oxide films 200 and 205 may be larger than the etchselectivity of the first mask film 210 with respect to the oxide films200 and 205.

Referring to FIG. 9, by patterning the first mask film 210 and thesecond mask film 220, a first mask pattern 211 and a second mask pattern221 may be formed. The first mask film pattern 211 may have the firstthickness h1 like the first mask film 210, and the second mask filmpattern 221 may have the second thickness h2 like the second mask film220. The first thickness h1 of the first mask film pattern 211 may belarger than the second thickness h2 of the second mask film pattern 221.More specifically, the first thickness h1 of the first mask film pattern211 may be approximately twice to three times the second thickness h2 ofthe second mask film pattern 221.

Some portions of the upper surface of the upper supporter film 202 maybe exposed via the first mask film pattern 211 and the second mask filmpattern 221. The exposed portions of the upper supporter film 202 mayoverlap the landing pad 60 at least partially. For example, when viewedin a plan view, the exposed portions of the upper supporter film 202 mayoverlap portions of the landing pad 60. This is because a process offorming a hole is carried out on the exposed portions of the uppersupporter film 202, the first and second oxide films 200 and 205 locatedunder the upper support film 202 and the lower supporter film 201, suchthat a capacitor in the hole is electrically connected to the landingpad 60.

Referring to FIG. 10, a first etch process 400 of etching the uppersupporter film 202 and the second oxide film 205 may be carried out byusing the second mask film pattern 221 as an etch mask.

In some embodiments of the present disclosure, a part of the lowersupporter film 201 may be etched when the second oxide film 205 isetched.

As a result of the first etch process 400, a first hole 230 may beformed that penetrates the upper supporter film 202, the second oxidefilm 205 and the lower supporter film 201.

During the first etch process 400, an etchant for etching the uppersupporter film 202, the second oxide film 205 and the lower supporterfilm 201 may include, for example, C₄F₈ or C₄F₆ gas or a mixed gasthereof.

As described above with respect to the above-described exemplaryembodiment, the second mask film pattern 221 may also be damaged duringthe first etch process 400, such that the thickness of the second maskfilm pattern 221 may be reduced. The second mask film pattern 221 maynot be completely removed via the first etch process 400.

As a result of the first etch process 400, some portions of the uppersurface of the first oxide film 200 may be exposed. Alternatively, someportions of the upper surface of the lower supporter film 201 may beexposed via the first etch process 400.

Referring to FIG. 11, the second mask film pattern 221 remaining afterthe first etch process 400 is completely removed, such that the uppersurface of the first mask film pattern 211 is exposed.

The second mask film pattern 221 may be removed by wet etching. Forexample, the second mask film pattern 221 may be removed by using amixture of a hot sulfuric acid solution and a SC1 solution. By combiningthe wet etchants, the second mask film pattern 221 can be completelyremoved with no damage to the oxide films 200 and 205 and the upper andlower supporter films 201 and 202.

Referring to FIG. 12, a second etch process 410 of etching the firstoxide film 200 may be carried out by using the first mask film pattern211 as an etch mask. As a result of the second etch process 410, asecond hole 240 may be formed that penetrates the oxide films 200 and205 and the upper and lower supporter films 201 and 202 completely.

Performing the second etch process 410 may include removing the stoppinginsulation film 70 under the oxide film 200. As some portions of thestopping insulation film 70 covering the landing pad 60 are removed, theupper surface of the landing pad 60 may be exposed.

During the second etch process 410, the first mask film pattern 211 maybe damaged, such that the thickness of the first mask film pattern 211may be reduced.

During the second etch process 410, an etchant for etching the firstoxide film 200 and the stopping insulation film 70 may include, forexample, C₄F₈ or C₄F₆ gas or a mixed gas thereof.

Like the above-described exemplary embodiment, in the method offabricating a semiconductor device according to the another exemplaryembodiment of the present disclosure, the second hole 240 having a highaspect ratio is formed by using the first and second mask films 211 and221 having different etch selectivities with respect to the oxide films200 and 205.

For example, the first etch process 400 of etching the second oxide film205 is carried out by using the second mask film pattern 221 whichincludes a metal mask film and thus has a high etch selectivity withrespect to the oxide films 200 and 205, and then the second etch process310 of etching the first oxide film 200 is carried out by using thefirst mask film pattern 211 which includes a silicon mask film.

By doing so, the second hole 240 having a high aspect ratio can beformed, and the CD non-uniformity that may occur during the etching withthe second mask film 221 can be mitigated by the second etch process 410with the first mask film 211.

Subsequently, referring to FIG. 13, a lower electrode 250 is formed inthe second hole 240. Forming the lower electrode 250 may include, forexample, filling the second hole 240 with a conductive material, andthen removing the conductive material on the upper surface of the uppersupporter film 202 via an etch-back process or chemical mechanicalpolishing (CMP), etc.

Some portions of the side walls of the lower electrode 250 may come incontact with the lower supporter film 201 and the upper supporter film202. Accordingly, the lower electrode 250 may be supported by the lowersupporter film 201 and the upper supporter film 202.

Referring to FIG. 14, a third mask pattern 215 is formed such that itcovers the upper supporter film 202 and the lower electrode 250. Then,the upper supporter film 202, the lower supporter film 201, the secondoxide film 205 and the first oxide film 200 are removed via an opening303 in the third mask film pattern 215.

The third mask pattern 215 includes the opening 303 overlapping the areabetween the two lower electrodes 250.

Removing the upper supporter film 202, the lower supporter film 201, thesecond oxide film 205 and the first oxide film 200 may include removingthem by injecting C₄F₈ or C₄F₆ gas or a mixed gas thereof via theopening 303.

As the first oxide film 200 and the second oxide film 205 are removed,cavities 301 and 302 surrounded by the lower electrode 250 and the upperand lower supporter films 201 and 202 may be formed.

Subsequently, referring to FIG. 15, the third mask film pattern 215 isremoved. Then, a dielectric film 270 is formed conformally over thelower electrode 250 and the upper and lower support films 201 and 202,and an upper electrode 260 is formed on the dielectric film.

The dielectric film 270 may be formed conformally on the inner walls ofthe cavities 301 and 302 formed after the oxide films 200 and 205 areremoved.

By forming the lower electrode 250, the upper electrode 260 and thedielectric film 270, the capacitor 280 is formed.

As described above, by the method of fabricating a semiconductor deviceaccording to the another exemplary embodiment of the present disclosure,it is possible to form the second hole 240 having a high aspect ratioand the lower electrode 250 with which the second hole 240 is filled,thereby forming the capacitor 280 having a high aspect ratio. Thecapacitor 280 having a high aspect ratio can have increased capacitanceand can improve the operation reliability of the semiconductor device.

The embodiments of the present disclosure have been described withreference to the attached drawings, but it may be understood by one ofordinary skill in the art that the present disclosure may be performedone of ordinary skill in the art in other specific forms withoutchanging the technical concept or essential features of the presentdisclosure. Further, the above-described embodiments are merely examplesand do not limit the scope of the rights of the present disclosure.

What is claimed is:
 1. A method of fabricating a semiconductor device,the method comprising: forming an oxide film on a target layer; forminga first mask film on the oxide film, wherein the first mask filmcontains a semiconductor material and has a first thickness and a firstetch selectivity with respect to the oxide film; forming a second maskfilm on the first mask film, wherein the second mask film contains ametal and has a second thickness smaller than the first thickness and asecond etch selectivity with respect to the oxide film larger than thefirst etch selectivity; forming a second mask film pattern by patterningthe second mask film; forming a first mask film pattern by patterningthe first mask film; etching first portions of the oxide film by usingthe second mask film pattern as a first etch mask film; and etchingsecond portions of the oxide film by using the first mask film patternas a second etch mask film to form a hole, wherein the target layer isexposed via the hole.
 2. The method of claim 1, further comprising:completely removing the second mask film pattern after the etching thefirst portions of the oxide film by using the second mask film patternas the first etch mask film.
 3. The method of claim 2, wherein theremoving the second mask film pattern comprises removing the second maskfilm pattern by wet etching.
 4. The method of claim 1, wherein the firstthickness is between two to three times the second thickness.
 5. Themethod of claim 1, wherein the oxide film comprises a first oxide filmand a second oxide film formed on the first oxide film, and wherein theforming the oxide film on the target layer comprises: forming a lowersupporter film interposed between the first oxide film and the secondoxide film, and forming an upper supporter film interposed between thesecond oxide film and the first mask film.
 6. The method of claim 5,wherein each of the upper supporter film and the lower supporter filmcomprises a silicon oxynitride film.
 7. The method of claim 1, whereinthe first mask film comprises a silicon mask film, and the second maskfilm comprises a metal mask film.
 8. The method of claim 7, wherein theforming the first mask film comprises depositing a silicon and/or adoped silicon.
 9. The method of claim 7, wherein the forming the secondmask film comprises depositing at least one of tungsten, tungstennitride, tungsten carbide, aluminum, aluminum oxide, titanium, titaniumoxide and tungsten silicide.
 10. The method of claim 1, furthercomprising: forming a lower electrode to fill a second hole; removingthe oxide film; forming a dielectric layer conformally over the lowerelectrode and the target layer; and forming an upper electrode on thedielectric layer.
 11. A method of fabricating a semiconductor device,the method comprising: forming an isolating film to define an activearea in a substrate; forming a gate in the active area; forming aninterlayer insulation film on the substrate, a bit line feature, and alanding pad in the interlayer insulation film, wherein the landing padis electrically connected to the active area; forming an oxide film onthe interlayer insulation film; forming a first mask film pattern on theoxide film and a second mask film pattern on the first mask filmpattern; forming a first hole penetrating the oxide film to a depth byusing the second mask film pattern; forming a second hole by etching aremaining portion of the oxide film by using the first mask filmpattern, wherein the landing pad is exposed via the second hole; andforming a capacitor electrically connected to the landing pad via thesecond hole.
 12. The method of claim 11, wherein the first mask filmpattern has a first thickness, and the second mask film pattern has asecond thickness smaller than the first thickness.
 13. The method ofclaim 11, wherein forming the capacitor comprises: forming a lowerelectrode to fill the second hole; removing the oxide film; forming adielectric layer conformally over the lower electrode and a targetlayer; and forming an upper electrode on the dielectric layer.
 14. Themethod of claim 11, wherein the first mask film pattern contains anoxide film containing silicon or nitride; and the second mask filmpattern contains an oxide film contains metal.
 15. The method of claim11, wherein the first mask film pattern has a first etch selectivitywith respect to the oxide film, and the second mask film pattern has asecond etch selectivity with respect to the oxide film, wherein thesecond etch selectivity is larger than the first etch selectivity.
 16. Amethod of fabricating a semiconductor device, the method comprising:forming an oxide film on an interlayer insulation film; forming a firstmask film on the oxide film, wherein the first mask film has a firstthickness and a first etch selectivity with respect to the oxide film;forming a second mask film on the first mask film, wherein the secondmask film has a second thickness and a second etch selectivity withrespect to the oxide film; forming a second mask film pattern bypatterning the second mask film; forming a first mask film pattern bypatterning the first mask film; forming a first hole penetrating theoxide film to a depth by using the second mask film pattern as a firstetch mask; forming a second hole by etching a remaining portion of theoxide film by using the first mask film pattern as a second etch mask,wherein a landing pad in the interlayer insulation film is exposed viathe second hole; and forming a capacitor electrically connected to thelanding pad via the second hole, wherein the first thickness is largerthan the second thickness and the first etch selectivity is smaller thanthe second etch selectivity.
 17. The method of claim 16, wherein formingthe capacitor comprises: forming a lower electrode to fill the secondhole; removing the oxide film; forming a dielectric layer conformallyover the lower electrode and a stopping insulation film; and forming anupper electrode on the dielectric layer.
 18. The method of claim 16,wherein the oxide film comprises a first oxide film and a second oxidefilm formed on the first oxide film, and wherein the forming the oxidefilm on the interlayer insulation film comprises: forming a lowersupporter film between the first oxide film and the second oxide film,and forming an upper supporter film between the second oxide film andthe first mask film.
 19. The method of claim 16, wherein the first maskfilm comprises a silicon mask film, and wherein the forming the firstmask film comprises depositing a silicon and/or a doped silicon.
 20. Themethod of claim 16, wherein the second mask film comprises a metal maskfilm, and wherein the forming the second mask film comprises depositingat least one of tungsten, tungsten nitride, tungsten carbide, aluminum,aluminum oxide, titanium, titanium oxide and tungsten silicide.